1. Technical Field
The present invention relates to a MEMS sensor (Micro Electro Mechanical Sensor), a MEMS sensor manufacturing method, and an electronic device.
2. Related Art
As a silicon MEMS acceleration sensor with a CMOS integrated circuit, for example, a reduction in size and cost of the MEMS sensor is rapidly progressing. The application and market of the MEMS sensor are expanding. In a main device form, an IC chip that converts a physical quantity into an electric signal and outputs the same is made into one package by a mounting process after a wafer process inmost cases. For achieving an extreme reduction in size and cost, a technique of integrally forming a sensor chip and an IC chip by a wafer process is required (refer to JP-A-2006-263902).
In a capacitive MEMS sensor (capacitive MEMS physical quantity sensor) that detects a physical quantity such as acceleration or pressure based on change in capacitance value of a capacitor configured by a movable electrode portion and a fixed electrode portion, the movable electrode portion is formed integrally with a movable weight portion. The movable electrode portion is displaced along with the displacement of the movable weight portion to change the gap or facing area between the movable electrode portion and the fixed electrode portion, which causes the movement of charge. The movement of charge is converted into an electric signal (voltage signal) by, for example, a C/V conversion circuit including a charge amplifier, so that the physical quantity is detected. Moreover, in a typical MEMS sensor in which a movable electrode portion is integrated into a movable weight portion, the height of the movable electrode portion is the same as that of the movable weight portion (refer to FIGS. 4 and 5 in JP-A-2005-140792).